1. Field of the Invention
The present invention relates to a biomedical electric wave sensor, particularly to a biomedical electric wave sensor capable of pushing aside hair.
2. Description of the Prior Art
The electric wave signal measurement has been widely applied in many fields such as military, biomedicine and man-machine systems and is used in biomedicine field for measuring EEG (electroencephalography), ECG (electrocardiography), EMG (electromyography) and so on.
Conventional electric wave signal measuring instruments usually adopt wet electrodes, which require conducting gel for proper functioning. However, the conducting gel may cause illness of patients, e.g. allergy or swelling, and can not be long-acting since the conductivity thereof would decrease with time.
Dry electrodes have been recently developed to resolve the aforementioned problems of wet electrodes. Most of the available dry electrodes are made by microstructure process, e.g. MEMS (Micro Electro Mechanical Systems), or CNTs (carbon nanotubes) and used in the form of penetrating the epidermis when in contact of the skin for achieving better conductivity and measurement.
As mentioned, the dry electrodes need to be in contact with the skin to actuate; however, the dry microstructure electrodes have short length (about 0.1 mm to 0.2 mm) and hair may cause intervention problems when used in practice. For example, the dry microstructure electrodes may be blocked by hair when applied for multiple point EEG measurement. Cutting the hair in advance is the main measure taken for now to overcome the intervention problem caused by hair; however, it is neither convenient nor applicable in many situations.
Besides, one of the development goals for EEG systems is being used as a portable device for common applications in addition to medicine field, e.g. a monitor system for monitoring long time drivers, or a computer system controlled by human brain. Thus, it is obviously not desirable to cut the hair when using these portable devices with EEG systems.
To sum up, it is now a current goal to develop a novel biomedical electric wave sensor which overcomes the intervention problem caused by hair.